Figure 2: Time dependence of the composition of the polymerization mixtures.

Mixtures are monitored by SEC equipped with a refractive index (RI) detector, showing the different reaction pathways. (a) HB polyBDA, indicating that the divinyl monomer first underwent a large-scale linear oligomerization (<1 h) followed by oligomer combination (>1 h); (b) cyclized polyBDA, showing the unimodal peaks typically at initial stages (<5 h) and multimodal peaks appearing later (>5 h). Significant multimodality in the case of HB polyBDA, especially for low and moderate molar masses, is not observed in the case of single-cyclized polyBDA. This strongly supports the expected differences in terms of mechanism: in the case of single-cyclized polyBDA (almost exclusively intramolecular cyclization), the increase of molar masses is only owing to propagation, whereas in the case of HB, it is mainly owing to intermolecular combination.